Pressure indicating bung with self-locking insertion feature

ABSTRACT

A bung in which the side walls are relaxed upon insertion into a bung hole, as in a beer barrel, but which subsequently become compressed when pressure in the barrel or similar vessel pushes against a bottom wall connected to the side wall, compressing the side wall with bellows action, thereby forcing corrugated side wall edges into contact with the bung wall. Pressure on the bottom wall forces the bottom wall upward so that an elongated member attached to the bottom wall raises as the bottom wall is raised, thereby indicating the extent of pressure on the bottom wall.

United States Patent [191 Souza PRESSURE INDICATING BUNG WITHSELF-LOCKING INSERTION FEATURE [75] Inventor: Augustine A. Souza, SanJose, Calif.

[73] Assignee: Robert N. Noyce, Los Altos, Calif.

[22] Filed: Aug. 10, 1972 [21] Appl. No.: 279,314

[ 51 July 3,1973

3,473,686 .10/1969 Kusserow 217/108 3,574,312 4/1971 Miller 220/2453,675,722 7/1972 Balmes, Sr. 116/70 [57] ABSTRACT A bung in which theside walls are relaxed upon insertion into a bung hole, as in a beerbarrel, but which subsequently become compressed when pressure in thebarrel or similar vessel pushes against a bottom wall connected to theside wall, compressing the side wall with bellows action, therebyforcing corrugated side wall edges into contact with the bung wall.Pressure on the bottom wall forces the bottom wall upward so that anelongated member attached to the bottom wall raises as the bottom wallis raised, thereby indicating the extent of pressure on the bottom wall.

11 Claims, 6 Drawing Figures PRESSURE E Elg. i-

PRESSURE INDICATING BUNG WITH SELF-LOCKING INSERTION FEATURE BACKGROUNDOF THE INVENTION The invention pertains to closures for pressure vesselsand more particularly to self-sealing closures for pressure vesselswhich also serve to indicate the extent of pressure within the vessel,as in a beer barrel.

Barrel bungs with corrugated side walls are known, both in cases whereinthe corrugations are formed before insertion into a bung and in caseswhere corrugations are formed in situ by insertion of an expansible toolinto the bung and rotation thereof for deforming the side wallsoutwardly to grip the bung surface. Further, various types ofpressure-indicating closures are known wherein the extent of deformationof a closure member is indicative of the pressure thereon.

A problem with corrugated wall barrel bungs of the prior art is that inthe case where the corrugations were formed before insertion into thebung hole, the bung was difficult to insert into the hole. On the otherhand, in the case where the corrugation was formed in situ, the closureprocess was time consuming and commercially unfeasible except when doneby machine.

An object of the present invention is to provide a hung withself-locking corrugated walls which become firmly locked in positionupon pressurization of the vessel defining the bung hole. A furtherobject is to provide a bung with a pressure indicator which becomesoperative upon locking of the bung side walls in place.

Still another objectis to provide a bung which implodes when pressure onthe outside of the bung exceeds the strength of the bung materialthereby keeping the bung from becoming a missile and possibly saving thepressure vessel from destruction.

SUMMARY OF THE INVENTION The above objects are achieved in a bung havingan annular side wall with an externally corrugated wall surface with anexpansible rim at the bottom of the side wall. Connected to the rim is aconical bottom wall with a central zone which is somewhat thinner thanthe surrounding area, allowing the conical wall to flatten when pressureoutside the bung increases compared to the pressure inside. Excesspressure on the outside of the bottom wall will tend to flatten it,thereby enlarging the expansible rim and providing a self-lockingclosure of the bung in the bung hole while simultaneously forcing sidewall corrugations into tight contact with the bung hole wall. The bottomwall is also provided with an elongated member mounted above the centralzone of the bottom wall and extending upwardly. When the bottom wallflattens in response to pressure, thereby moving upward toward the planeof the expansible rim, the elongated member moves upward, therebyindicating pressure on the bottom wall.

An annular top flap is mounted transversely across the side wall whichserves as a reference for the elongated member which may pass throughthe center of the flap. Thus, once pressure is applied to the bottomwall of the bung, the bung will both lock itself in the bung hole andwill indicate pressure within the vessel which the bung is closing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective of theapparatus. FIG. 2 is a partial cut-away of the apparatus.

FIG. 3 is a side cut-away operational view of the apparatus shown seatedin a barrel.

FIG. 4 is a second side cut-away operational view of the apparatusseated in a barrel under pressure.

FIG. 5 is another operational view of the apparatus seated in a barrelunder further pressure.

FIG. 6 is a top view of the apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a perspective viewof the pressureindicating bung 12 of the present invention. Such a bungis intended to fit in the bung hole of barrels, kegs, bottles, andsimilar vessels. For a given type of barrel, for example the standardaluminum beer barrel or keg, uniform bung hole sizes have been adopted.Thus, the dimensions of the present bung are selected to fit in suchstandard size bung holes.

An annular side wall 14 has a flexibly corrugated wall surface, similarto a bellows. The corrugations are spaced generally parallel to eachother and parallel to the plane of the bung hole, except that thecorrugations may have a slight pitch when, for manufacturing purposes,it is convenient to form a screw thread wall structure. This enables thewall surface corrugations to grip the interior of the bung hole when thecorrugations radially expand. A lower annular portion of the side wallcomprises an-expansible rim 16, which is connected to a bottom wall 18.The expansible rim is designed to reside below the bung hole so thatradial ex- "pansion of the rim will prevent removal of the bung nectedto a radially outwardly extending lip 20 and sealed thereto. Lip 20includes tabs 22 for gripping the bung. An annular top flap 24 isconnected to lip 20 by means of a flexible hinge 26 which has an outerdiameter which is at least as great as the inner annular side walldiameter, so that the flap 24 can cover the interior of the bung 12. Theannular flap 24 defines an aperture through the center of a diameterwhich is sufficient to allow the passage therethrough of an elongatedpressure-indicating member 28 which is mounted to bottom wall 18 andwhich is described hereinafter.

FIG. 2 shows the manner of closure of the flap 24 over the lip whereinthe direction of full closure is indicated by the arrow in the figure.The pressureindicating member 28 fits through the aperture 30 in thefigure when the flap 24 is fully closed into the lip 20.

FIG. 3 shows an operational view of the apparatus seated in a barrel 13wherein the side wall 14 is corrugated with bellows or accordion typepleats 15 so that when no pressure exists on the bottom wall 18 of thebung 12 the side wall is fully distended and the bung 12 will easily fitinto a bung hole defined by walls 17 without appreciable friction. Withlow pressure or no pressure on the bottom wall, corrugations 15 have aminimum diameter. FIG. 3 also shows that bottom wall 18 is generallyconical in configuration with a central zone defining a dimple 32 whichis thinner than the surrounding area. This allows the conical wall'toflatten in response to pressure on the underside thereof.

While the terms under, bottom, top, upper, and side" are used withreference to the drawings, it will be understood that these terms arerelative and that it is not necessary for the bung to assume any givendirection for operation as described herein.

It will be noted that the elongated pressure-indicating member 28 ismounted with one end directly above the dimple 32 and that the length ofindicator 28 when side walls 14 are fully distended is such that the tip34 of indicator 28 is below the plane of flap 24.

FIG. 4 shows bung 12 with a greater pressure applied to the underside ofthe bottom wall 18 than exists on the upper side. Pressure is indicatedby the arrows in the figure. The above mentioned pressure causes thebottom wall to flatten, pivoting about the dimple 32. The material ofthe bottom wall is a semi-stiff material such as plastic made of athickness so that the sides of the conical bottom 18 will remain stiffyet will pivot at the dimple 32. As the conical bottom wall 18 flattens,the bottom expansible rim 16 of the side wall 14 is urged outward. Atthe same time, the upward pressure on the bottom wall tends to compressthe side wall, thereby outwardly urging the corrugations of the sidewall 14. The corrugations then contact the interior of the bung hole andtend to lock the bung into place. Since the expansible rim 16 extendsradially even further than the corrugations of the side wall, the bungwill remain firmly locked in place in those cases where the thickness ofthe bung hole is less than the length of the side wall 14.

It will be noted that the tip 34 of the pressureindicating member 28 isprojecting slightly through the aperture 30, thereby indicating theextent of pressure on the bottom wall. The tip 34 may be marked withgraduated fiducial markings which are calibrated against a standard sothat the extent of projection of the tip 34 through hole 30quantitatively defines the pressure on the bottom wall.

FIG. shows the bung 12 of the present invention with bottom wall 18fully flattened due to pressure on the underside of the bottom wall inthe direction of the arrows. The rim 16 has fully outwardly extended inresponse to the enlarged diameter due to flattening of the conicalbottom wall 18. This flattening causes the pressure-indicating member 28to project still further through the aperture 30 of flap 24. Theincreased pressure causes a further outward projection of thecorrugations of the side wall 14, toward a maximum diameter therebyincreasing friction of the bung 12 against the bung hole due to theincreased pressure on the bottom wall 18 which outwardly urges thecorrugations 15. If pressure in the key which defines the bung holeincreases still further, the elastic limits of the bung material will beovercome and the walls will collapse due to the increased pressure,thereby releasing the excessive pressure without causing the bung tobecome a projectile. The bung material is usually a plastic, such aspolyvinylchloride, and is designed to yeild at the side walls inresponse to the predetermined high pressure substantially before thepressure vessel yields. Yield at the side walls is controlled by theyield strength of the selected material and its shape. The yieldstrength may be verified empirically by testing. By insuring that thebung will yield at a substantially lesser pressure than the pressurevessel, pressure vessels can be saved from damage.

FIG. 6 shows a top view of the constructional detail of the flap 24 andthe lip 20 on which it closes. Note that the flap 24 includes a closure36 which fits into a corresponding groove 38 and projects slightlythereover for locking purposes if desired. A second groove 40 isprovided on the opposite side of the lip 20 to receive a portion of thehinge 26 when it is folded over so that the flap 24 can rest in agenerally flat position with respect to the plane of the lip 20. Thus,the plane of lip 20 becomes a reference surface for sighting the extentof the projection of the pressure-indicating member 28 through theaperture 30 defined in the annular flap.

The entire apparatus lends itself to construction by injection moldingtechniques. Because of the construction as described above, the entireapparatus may be molded in one piece. Thus, the apparatus is simple,economical, and easy to use.

When the apparatus is inserted into a bung hole of a pressure vesselwhich is at atmospheric pressure, the bung easily travels into itsresting place with the lip 20 resting against the perimeter of the bunghole. As soon as pressure begins to build, for example upon filling thevessel, the increased pressure forces the conical bottom wall 18 upward,thereby compressing side wall 14, forcing bung corrugations into firmcontact with the bung hole walls and expanding the expansible rim, andproviding self-locking closure of the bung in the bung hole. It will benoted that two separate forces lock the bung into place: first, radialexpansion of side wall corrugations and second, an even further radialexpansion of the expansible rim. At the same time upward movement of thewall gives a pressure indication which, if calibrated, can indicate thedegree of filling when pressure is directly related to such filling.When the vessel is emptied and returned to atmospheric pressure, thebung may be easily removed upon distention of the side walls, therebyallowing inspection of the vessel.

What is claimed is:

l. A pressure-indicating bung for a pressure vessel comprising anannular side wall having an externally corrugated, bellows type annularside wall surface, an expansible rim at the bottom of said side wall, aconical bottom wall connected to said expansible rim in sealedrelationship therewith, said bottom wall having a central zone thinnerthan the surrounding area whereby said conical wall will flatten inresponse to pressure thereon thereby radially expanding said expansiblerim and said corrugated wall surface, and an elongated member mounted atone end above said central zone of said bottom wall and upwardlyextending therefrom for indicating pressure in response to movement ofsaid bottom wall.

2. The apparatus of claim 1 further defined by a radially outwardlyextending lip connected to the top of said side wall.

3. The apparatus of claim 2 further defined by an annular top flaphaving a diameter at least as great as said annular side wall and hingedto said lip at one point for mounting over said lip.

4. The apparatus of claim 2 further defined by tabs attached to said lipfor gripping said bung.

5. The apparatus of claim 1 wherein the central thin zone of the bottomwall comprises a dimple at the apex of said conical bottom wall.

6. The apparatus of claim 1 further defined wherein said corrugated sidewall surface is a bellows whereby the diameters of said corrugations areminimized with low pressure on said bottom wall and maximized with highpressure whereby said bung locks itself in place upon application ofpressure upon said bottom wall.

9. The apparatus of claim 8 wherein said elongated member is graduatedfor indicating amounts of pressure.

10. The apparatus of claim 1 wherein said bung is made of a materialwhich has a yield strength substantially less than said pressure vessel.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO. Dated yInventor(s) Augustine A. Souza It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Col. 3', line 49 Change "key"; to "keg".

Col. 6, Claim 11 Claim ll has been left out in its entirety;

Signed and sealed this 27th day of November 1973.

(SEAL) Attest:

EDWARD M.FLE TCHER,JR. RENE D. TEGTMEYER Attesting' Officer ActingCommissioner of Patents FORM PO-105O (10-69) j -pc smug-peg a u.s,GOVERNMENT PRINTING OFFICE: I969 o-sse-au.

1. A pressure-indicating bung for a pressure vessel comprising anannular side wall having an externally corrugated, bellows type annularside wall surface, an expansible rim at the bottom of said side wall, aconical bottom wall connected to said expansible rim in sealedrelationship therewith, said bottom wall having a central zone thinnerthan the surrounding area whereby said conical wall will flatten inresponse to pressure thereon thereby radially expanding said expansiblerim and said corrugated wall surface, and an elongated member mounted atone end above said central zone of said bottom wall and upwardlyextending therefrom for indicating pressure in response to movement ofsaid bottom wall.
 2. The apparatus of claim 1 further defined by aradially outwardly extending lip connected to the top of said side wall.3. The apparatus of claim 2 further defined by an annular top flaphaving a diameter at least as great as said annular side wall and hingedto said lip at one point for mounting over said lip.
 4. The apparatus ofclaim 2 further defined by tabs attached to said lip for gripping saidbung.
 5. The apparatus of claim 1 wherein the central thin zone of thebottom wall comprises a dimple at the apex of said conical bottom wall.6. The apparatus of claim 1 further defined wherein said corrugated sidewall surface is a bellows whereby the diameters of said corrugations areminimized with low pressure on said bottom wall and maximized with highpressure whereby said bung locks itself in place upon application ofpressure upon said bottom wall.
 7. The apparatus of claim 1 furtherdefined wherein said corrugated side wall surface comprises screwthreads.
 8. The apparatus of claim 2 further defined wherein saidelongated member extends from said bottom wall to slightly below saidannular flap when pressure on both side of said bottom wall is equal. 9.The apparatus of claim 8 wherein said elongated member is graduated forindicating amounts of pressure.
 10. The apparatus of claim 1 whereinsaid bung is made of a material which has a yield strength substantiallyless than said pressure vessel.
 11. A one-piece moldedpressure-indicating bung for a pressure vessel comprising an annularside wall having an externally corrugated bellows type wall surface, aradially outwardly extending lip at the top of said wall, and anexpansible rim at the bottom of said wall, a conical bottom wallconnected to said expansible rim in sealed relation therewith, saidbottom wall having a central zone thinner than the surrounding areawhereby said conical wall will flatten in response to pressure thereonthereby expanding said expansible rim and said corrugated wall surface,an annular top flap having an outer diameter at least as great as saidannular side wall and hinged to said lip at one point for mounting oVersaid lip, and an elongated member mounted at one end above said centralzone of said bottom wall and upwardly extending therefrom for indicatingpressure upon movement of said bottom wall by projection through saidannular top flap.